ORGANIZATION AND BASIS OF PRESENTATION - Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cash paid for (received from):
Interest, net of amount capitalized	$ 86.5	$ 59.3
Income taxes, net of refunds	0.2	(0.1)
Right-of-use assets obtained in exchange for new operating lease liabilities	2.6	2.2
Non-cash investing transactions:
Property, plant and equipment additions	75.7	47.1
Non-cash financing transactions:
Issuance of stock for compensation and reinvested dividends	0.9	0.5
Right-of-use assets obtained in exchange for new finance lease liabilities	3.1	2.3
Variable Interest Entities
Cash paid for (received from):
Interest of VIEs	0.6	1.0
Evergy Kansas Central
Cash paid for (received from):
Interest, net of amount capitalized	37.4	32.6
Income taxes, net of refunds	0.2	0.0
Right-of-use assets obtained in exchange for new operating lease liabilities	2.6	0.0
Non-cash investing transactions:
Property, plant and equipment additions	52.5	27.1
Non-cash financing transactions:
Right-of-use assets obtained in exchange for new finance lease liabilities	1.9	2.3
Evergy Kansas Central | Variable Interest Entities
Cash paid for (received from):
Interest of VIEs	0.6	1.0
Evergy Metro
Cash paid for (received from):
Interest, net of amount capitalized	18.7	19.6
Right-of-use assets obtained in exchange for new operating lease liabilities	0.0	2.2
Non-cash investing transactions:
Property, plant and equipment additions	17.8	15.9
Non-cash financing transactions:
Right-of-use assets obtained in exchange for new finance lease liabilities	$ 1.2	$ 0.0